Machines for lapping insulating material on to electric conductors



March 3, 1959 Filed Jan. 13, 1958 A. MACKENZIE EI'AL W. MACHINES FORLAPPING INSULATING MATERIAL ON TO ELECTRIC CONDUCTORS 7 Sheets-Sheet 1Inventors Wr'lliam #IexmJw/Iackenzie 8 William l/zrr y (larlnJlart A[form eys March' 3, 1959 w. A. MACK/ENZIE ET AL 2,875,571 V MACHINES FORLAPPING INSULATING MATERIAL ON TO ELECTRIC CONDUCTORS Filed Jan. 13,1958 '7 Sheets-Sheet 2 A ttorney:

March 3, 1959 Filed Jan. 15, 1958 w. A. MACKENZIE ETAL MACHINES FORLAPPING INSULATING MATERIAL ON T ELECTRIC CONDUCTORS 7 '7 Sheets-Sheet 5Inventor wilhim lie/tender Mackenzie a William A arm Clark: J'lar/rAttorneyx March 3, 1959 w. A; MACKENZIE ET MACHINES FOR L AL 2,875,571APPING INSULATINGCMATERIAL ON TO ELECTRIC CONDUCTORS Filed Jan. 13. 19587 Sheets-Sheet 4 F/G, 2b,

. In ventor: William lie/lander flar /1Z1? 17 A ttomey:

w. A. MACKENZIE ETAL 2,875,571 MACHINES FOR LAPPING INSULATING MATERIALON TO March 3, 1959 A ELECTRIC CONDUCTORS Filed Jan. 13, 1958 '7Sheets-Sheet 5 III 5 Inventor-s William Iletandrlbdenn? 9 William l/arydiaries ,SZark Bya5 V Attorneys March 3, 1959 w A. MACKENZIE ETAL2,875,571

MACHINES FOR LAPPING INSULATING MATERIAL ON T ELECTRIC CONDUCTORS FiledJan. 13, 1958 '7 Sheets-Sheet 6 1211091110725 William lkmaJerfimnzn" dWilliam flan] (Zerkr ,S'fart A ttorne y:

March 3, 1959 w. A. MACKENZIE ETAL 2,875,571 MACHINES FOR LAPPINGINSULATING MATERIAL ON TO ELECTRIC CONDUGTORS Filed Jan. 13, 1958 V 7Sheets-Sheet 7 'F lG/O. o

w A O o 97 '92 99 F/GQ9. a

,4; Aim/9W A ttorn e 31.:

United States Patent MACHINES FOR LAPPING INSULATING MATE- RIAL ON TOELECTRIC CONDUCTORS Application January 13, 1958, Serial No. 708,588

Claims priority, application Great Britain January 18, 1957 14 Claims.(Cl. 57-19) I This invention relates to machines for lapping insulatlngtape, e. g. paper strip, on to electric conductors over an open lappingof a spacing material, e. g. paper string, which spacing material maybe, and generally will be, applied by the same machine immediately priorto the application of the insulating tape. For convenience the conductorwill hereinafter be referred to as a wire.

The object of the invention is to provide a machine which works at highspeed and which requires the minimum of supervision since it isautomatically stopped when it requires attention.

In accordance with the invention the insulating tape applying machine isprovided with automatic stopping means which is brought into operationwhen the wire having an open lapping of spacing material ceases to becovered by insulating tape, the automatic stopping means including anelectric circuit comprising the wire to which the insulating tape isbeing applied and atleast one electric contact which is adapted to bearagainst the wire between the turns of the spacing material when the Wireceases to be covered by the insulating tape, the contact or contactsbeing normally insulated from and held away from the wire by theinsulating tape lapped thereon.

Where more than one contact is used the contacts are all electricallyconnected, e. g. they may form part of a single conducting member.

We prefer to use a conducting member comprising a pulley over which thewire passes in its path from the insulating tape lapping head, thepulley being so shaped as to provide a number of electric contacts whichtouch the wire if the insulating tape is no longer applied over thespacing material. The pulley may, for example, carry metal members whichact as the contacts; the members may, for example, consist of conductivecylinders, e. g. copper cylinders, mounted transversely in the pulleygroove and spaced apart around the periphery of the pulley by a distancewhich is not equal to or is not a multiple of the lay of the paperstring. or other spacing material.

When the open lapping of spacing material is applied to the wire in thesame machine an automatic stopping means may also be arranged to comeinto operation by the making of an electric circuit including the wireand an electric contact which is urged towards, but normally held out ofcontact with, the wire by the spacing material. This circuit may includea pair of coaxially mounted discs which are normally insulated from eachother and are pressed lightly towards each other but are normally heldapart by the lapping of spacing material applied to the wire. When thewire is bare the two discs press against it to complete the circuit. Thediscs are preferably free to rotate and arranged so that the wire passesalong a chord near the outer edges of the discs.

Both the tape lapping head and the haul-off capstan ice electric motorand, when the spacing material is applied simultaneously with the tape,the head by which it is applied is preferably also driven by this motor.The head for applying the spacing material is conveniently mountedbeneath and coaxially with the tape head so that the wire can passvertically upwards through the two heads. The device for. detecting abreak in the spacing material is then mounted between the two heads.

In order to attain rapid stopping of the machine we prefer to employstopping means which when brought into operation, effects or effect areversal of the power supply to the field coils of the motor for acontrolled time.

The invention is particularly applicable to machines of the type inwhich the coil of tape being applied to the wire is mounted coaxiallywith the wire and the lapping head is driven by an electric motor with ahollow shaft through which the wire passes.

We prefer also to provide means for stopping the motor when the coil oftape from which tape applied to the wire is being withdrawn is almostexhausted. When, as is customary, the coil from which the tape isapplied to the wire consists of a flat pad supported eoaxially with themotor shaft on or above a horizontal rotating table mounted on the motorshaft, the arrangement for stopping the motor when the pad is almost runout may include a first electric contact pressed on to the pad near itscentre by a spring contact arm mounted on the cable and a secondelectric contact on the surface of the table immediately beneath thefirst contact. The first contact will normally be separated from thesecond contact by the pad but when the pad is almost run out it will befree to move downwards and make contact with the second contact. Thefirst contact, mounted on the spring arm, may be earthed through themachine frame and the second contact insulated from the table andconnected to the appropriate relay circuit through a slip ring andbrush. The first contact may be associated with or form part of meansfor braking the pad to restrain its rotation relative to the table forthe purpose of controlling the tension in the tape.

Means for stopping the motor when a predetermined length of wire hasbeen passed through the machine may also be provided.

The invention will now be described by way of example with reference tothe accompanying drawings wherein Figure l is a front elevation of amachine adapted to apply an open lapping of paper string and a lappingof paper tape to a wire;

Figures 2, 2a and 2b are together a sectional elevation of the machineof Figure 1, taken along the line Il-II for the insulated wire arepreferably driven by a single and drawn to a larger scale, but with thetop portion of the machine omitted; V

Figure 3 is a cross-section of the machine taken along the line III-IIIof Figure 2a;

Figure 4 is a cross-section of the machine taken along the line IV-IV ofFigure 2a;

Figure 5 is a cross-section of means for detecting whether or not theopen lapping of paper string has been applied tothe wire;

Figure 6 is a cross-section of a pulley for detecting whether or not thelapping of paper tape has been applied to the wire;

Figure 7 is a sectional elevation of the paper tape applying head takenperpendicular to the view of Fig ure 2;

Figure 8 is an electrical circuit for the machine;

Figure 9 is a sectional elevation of a switchforming part of themachine;

Figure 10 is a plan view of the tape applying head, partly broken away,and

Figure 11 is a diagrammatic elevation of means for actuating a switch bya counter.

The machine shown in Figure 1 is adapted to apply to a wire 1 an openlapping of paper string followed by a lapping of paper tape. Itcomprises a frame 2 which supports an induction motor 3 having a hollowspindle through which the wire passes. The wire to be covered, which maybe stored on a supply drum (not shown) or any convenient means, passesaround a pair of guide pulleys 4, 5 and upwardly through the hollowspindle of a string applying head 6. A sensing device 7 detects whetheror not the string has been applied. From the sensing device 7 the wirepasses upwardly through the hollow spindle of the motor 3, through thehollow spindle 5 of a paper tape lapping head 8 and over a pulley 9which acts as a sensing device to detect whether or not the paper tapehas been applied. The wire is then pulled downwardly by a capstan 10 andpasses over a guide pulley 11 and between the fingers of a finger guide12 to be wound on to a take-up drum 13.

The method by which the tape applying head, string applying head,capstan and take-up drum are all driven from the induction motor 3 willbe described with reference to Figures 2, 2a, 2b, 3 and 4. Referring toFigure 2,

the hollow spindle 14 of the tape applying head is screwed at its lowerend on to the upper end of the hollow spindle 15 of the motor and isthus driven directly. A hollow shaft 16 is keyed to the lower end of themotor spindle and is driven by the motor spindle. A gear train which ishoused in a block 42 fixed to the sleeve 39. Relative rotation betweenthe sleeve 39 and the shaft causes the block 42 and the blade 41 torotate relative to the shaft 35 and the shaft 35 is constrained to moveaxially backwards and forwards a distance equal to the length of thesuperimposed screwthreads. The end portions of these threads are soarranged to guide the blade from the left hand thread to the right handthread or vice versa and to reverse the shaft when the knife bladereaches the end portion of the appropriate thread. In this manner thetake-up drum is rotated at the angular velocity of the pulley 33 and isreciprocated at a rate which depends on the ditference between theangular velocity of the two pulleys 33 and 34.

The sensing device 7 which detects whether or not the open lapping ofpaper string is being applied to the wire is shown in detail in Figure 5and mounted on the machine in Figures 1 and 2a. It comprises a pair ofcoaxially mounted metal discs 43 which are normally insulated from eachother and are pressed lightly towards each other by a spring 44 but heldapart by the lapping of spacing material. When the wire is bare thediscs press against it to complete a circuit described below. The discsare free to rotate and are arranged so that the wire passes along achord near their outer edges.

The pulley 9 (see Figures 1 and 6), over which the wire passes after ithas passed through the insulating tape applying head, is made of metaland is insulated from the frame of the machine. It carries coppercylinders 45 spaced apart around its periphery by a distance which isnot equal to or is not a multiple of the lay of the paper string. Thecopper cylinders form part of the electric circuit described below andwhich is completed if the 1 wire comes into contact with one of thecopper cylinders lower end of the hollow spindle 24 of the string apply-1 ing head (see Figures 2a and 4) to drive the string applying head.

A wormed sleeve 25 is fastened to the outer surface of the hollow shaft16 and forms a worm gear with a worm wheel 26 which is coaxially fixedto a rotatable shaft 27 (see Figures 2a and 3) which is thereby drivenby the electric motor. At one end of the shaft 27 is the capstan 10. Atits other end is a friction clutch comprising a pair of discs 28 facedwith friction material29 and urged by a spring 30 to contact the outerfaces of a double pulley 31. Two V-belts 32 running in the pulleygrooves transmit the motor drive to two pulleys 33 and 34 (see Figure2b) by which a shaft 35 carrying the take-up drum 13 is both rotated andalso reciprocated along its axis to cause the wire to be evenly wound.The drum is coupled to the shaft 35 by a disc carrying pins 36.

The simultaneous rotation and reciprocation of the shaft 35 is achievedas follows. To the pulley 33 is fixed a member 37 which is provided witha stud which runs in a groove 38 in the shaft 35 so that when the pulley33 rotates it rotates the shaft 35 with it, irrespective (within limitsdictated by the length of the groove 38) of the longitudinal position ofthe shaft. The pulley 34 is fastened to a sleeve 39 surrounding theshaft 35, so that the sleeve rotates with the pulley 34. The diameter ofthe two pulley grooves in the double pulley 31 and the two diameters ofthe two pulleys 33 and 34 are so arranged that the pulley 33 rotatesmore quickly than the pulley 34 so that there is relative rotationbetween the shaft 35 and the sleeve 39, the angular velocity of relativerotation being equal to the difference between the angular velocity ofthe pulleys 33 and 34. The surface of the shaft 35 is provided with adouble groove 46) comprising a left hand thread superimposed on a righthand thread and in this groove fits a knife blade 41 through not beingcovered with insulating tape.

The tape lapping head 8 (see Figures 2 and 7) includes a two-part headguard 46, 47, the taping head spindle 14 and a freely rotatable table orplatform 48 which normally carries a pad or coil of paper 49. There isalso provided a sensing device which detects when the pad of paper isnearly used up. This sensing device may be seen by referring to Figure7. It comprises a spring arm 50 mounted at one end on a table orplatform 7 51 which is fixed to and rotates with the motor spindle 15and hence also with the taping head spindle 14. The other end of the arm50 is provided with a contact member 52 which is normally pressedagainst the pad by flexing of the arm 50, this position being shownchain dotted in Figure 7. In thisposition the contact member 52 acts asa brake for the pad and its table 48 to restrain its rotation relativeto the spindle of the taping head for the purpose of controllingthe-tension in the tape. When the pad is nearly run out the contactmember springs into contact with a contact member 53, located above andinsulated from the table 51 (this position is shown in full lines inFigure 7). The contact member 53 is electrically connected to a slipring 54 carried on the motor spindle, the connection between the contactmember 53 and the slip ring 54 being electrically insulated from thebody of the machine. A carbon brush 55 fixed to but insulated from theframe of the machine makes contact with the slip ring and iselectrically connected to the electric circuit described below to stopthe machine when the pad has nearly run out.

This circuit is shown in Figure 8 and functions as follows. The motorterminals 56 are connected to the power lines 57 through two heavycurrent relays 58, 59 the terminals 60, 61 of which are so arranged thatif the relay 58 (the forward relay) is energized the motor rotatesforward and if the relay 59 (the reverse relay) is energised the motorrotates in reverse. The actuating current for the two relays 58 and 59is controlled by a double-acting relay comprising a coil 62 and switchesderived through a transformer 63 from the power line independently ofthe actuating current supply for the forward and reverse relays. Thesecondary circuit of the transformer includes the coil 64 of aninterlock relay the contacts 65 of which break the power supply circuitto the forward and the reverse relay when the coil 64 is deenergised,thus ensuring that neither of these relays can be energised until thetransformer secondary is energised. A switch 66 in the transformersecondary circuit is operated by the head guard 46, 47 in such a waythat none of the relays can function until the guard. is shut.

The coil 62 of the double-acting relay is so connected that when it isnot energised its contects 67, 68 are in a position such that the powersupply circuit to the coil of the forward relay 58 is closed and whenits coil is energised this circuit is opened and the power supplycircuit to the coil of the reverse relay 59 is closed. In Figure 8 thecontacts 67 for the forward relay are closed and contacts 68 for thereverse relay are open.

One terminal of the transformer secondary is connected toone terminal ofthe coil 62 of the double acting relay through trip circuit contacts 85which are closed by the forward relay 58 when it is energised and areopened by it when it is de-energised; a pilot light 103 indicates whenthe trip circuit contacts are closed. The other terminal of thetransformer secondary is connected to the other terminal of the coil 62of the double-acting relay through a switch 102, a rectifier 69 and oneof a number of, paths. One of these paths 70 comprises the wire 1 towhich the open lapping of string is being applied and the string sensingdevice 7. A second path 71 is through the spring arm 50 and contactmembers 52, 53 to the slip ring 54 and carbon brush 55. A third path 72is through the wire and the pulley 9 over which the normally insulatedwire passes. Across the terminals of the coil 62 of the double-actingrelay are connected two capacitors 73 and, in parallel therewith, twoleakage resistors 74, to form a timing circuit.

The actuating supply circuits to the forward and reverse relays 58, 59are also under the control of a start push button 75, a stop push button76 and an inc push button 77.

In operating the machine the guard switch 66 must first be closed byclosing the two-part head guard 46, 47, and a main switch 101 must beclosed by hand, thereby completing a circuit to a pilot light 78,indicating that the sensing circuits 70, 71, 72 are operable, and alsoenergising the coil 64 of the interlock relay to close the switch 65.When the start button 75 is pressed the circuit to the forward relay 58is completed by the closing of contacts 79 on the start button andthrough closed contacts 80 on the stop button. At the same time contacts1% are opened. On releasing the start button the contacts 1% are closedand contacts 79 are opened but the forward relay is energised throughcontacts 81 forming part of the inch control, and a hold-on control 82held in position by the forward relay 58.

On pressing the stop button, the contacts 80 are opened, therebyde-energising the forward relay 58 and hence also the hold-on control32. The motor is no longer energised to rotate forward. Whilst the stopbutton is being pressed, the contacts 83 are held closed and complete acircuit to energise the reverse relay 59, thereby reversing theconnection to the motor. On releasing the stop button, the contacts 83are opened and contacts 80 are closed again but the motor is notenergised forwards because the hold-on control 82 is not made. Onpressing the inch button the circuit to the forward relay 58 iscompleted through contacts 84 and contacts 80 but the contacts 81 areopened when the contacts 84 are closed, and thus the hold on control isdisabled so that the motor is energised only whilst the inch button isbeing pressed. Whenv the inch button is released the contacts 81 areclosed and contacts 84 are opened thus disabling the clrcuit to theforward relay 58.

The automatic cut-out circuit acts as follows. Assuming that the motoris running forwards, that the switch 102 is closed and that the stringapplying head andtape applying head are functioning properly, if thetape breaks the wire makes contact with the pulley 9 and the coil 62 ofthe double-acting relay is energized through the rectifier 69 and at thesame time the capacitors '73 commence to charge. Immediately the coil 62of the double-acting relay is energised the contacts 67 are opened andthe contacts 68 are closed, thereby deenergising the forward relay 58and energising the reverse relay 59, and reversing the connections tothe motor. The forward relay 58, when it is tie-energised, opens thetrip circuit contacts 65 to break the power supply circuit to the doubleacting relay 62 and to the capacitors 73. The capacitors will nowdischarge through the leakage resistances 74 and through the coil of thedouble-acting relay, which will thus remain energised for a controlledtime depending on the capacitance of the capacitors and the value of theleakage resistance. At the end of this period the contacts of the doubleacting relay will be reversed, thus de-energising the reverse relay 59and stopping the motor.

At the same time as the forward reply 53 is de-energised, the hold oncontrol 82 is disabled so that when the contacts of the double-actingrelay reverse the motor will not be automatically restarted.

The circuit 71 for stopping the motor when the pad is almost run out isconnected in parallel with the circuit 72 for stopping the motor whenthe tape ceases to be applied to the wire, thus a similar sequence ofoperation is initiated when the pad is almost run out. The circuit 70operates similarly when a break occurs in the spacing materim. A counteris also provided which measures the length of wire passing through themachine This counter operates a switch 86 which is tripped when thelength of wire to which the counter is set has been covered by themachine.

When one of the circuits for automatically stopping the machine iscompleted for too short a time to charge the capacitors, the forwardrelay 58 is de-energised, the trip circuit contacts are opened, the holdon the control 82 is disabled and the machine idles to rest withoutreverse braking.

As already mentioned, none of the relays can function until the two-parthead guard 46, 47 is closed, thereby closing the contacts 66 of theguard switch which is shown in detail in Figure 9 and mounted on thehead as seen in Figure 1. This switch comprises an upper and lowercasing, the lower casing 87 being fixed to the fixed part 46 of the headguard and the upper casing 88 being fixed to the movable part 47 of thehead guard. Within the lower casing are the contact 66 (see also Figure8) one being connected to a terminal of the transformer secondarywinding and the other being connected to a. terminal of the interlockrelay 64. A plunger 89 in the lower casing is normally urged by a spiralspring 90 out of engagement with the contacts 66. On closing the movablepart 47 of the head guard the end of an adjustable screw member 91engages the top of the plunger and forces it into engagement with the:contacts which are thereby bridged by the bottom end of the plunger andcomplete the circuit for the transformer secondary winding.

The head guard includes a mechanical locking arrangement which may beseen by reference to Figures 2 and 10 and which prevents an operatoropening the head guard until the speed of rotation of the motor spindlehas fallen to a very low value. The lock comprises an actuating member92 slidably mounted for longitudinal movement on the base of the lowerpart 46 of the guard in a direction towards and away from the motor.shaft. Its outer end is provided with a manually operable but,-

ton 93 fitting into a cover 94 ('see also Figure l). A.

spring 95 is fastened at one end of a bell crank lever 96, the other endof which fits into an indentation in the actuating member therebylocking the actuating member in the position shown in Figure 10. Theactuating member has a T-shaped lug 97 which fits into a complementaryT-shaped slot on a metal strip 98 fixed to the movable part 47 of thehead guard when the actuating member is in its outer position. Thus inthis position the movable part 47 of the head guard is locked to thefixed part. When the actuating member is in its inmost position the lug97 is clear of the metal strip 98 and the movable part of the head guardmay be opened. If the motor is rotating, the actuating member isprevented from being moved inwardly by a toothed wheel 99, coaxiallyfixed to the motor spindle, which makes contact with the pointed innerend of the member 92. Since the lock cannot be released until thepointed end of the actuating member is fitted between two of the teeth,the actuating member cannot be forced into the guard release positionuntil the motor spindle and hence the tape lapping head is stationary ormoving very slowly.

The means by which the counter which measures the yardage of wirepassing through the machine closes the switch 86 when a desired lengthof wire has passed through is shown in Figure 11. The counter, which isof the kind comprising a number of interconnected drums each marked onits periphery with the numbers -9, is supported on the frame of themachine by a bracket 104 (see Figure 1) and is driven by a reductiongear coupled to the spindle of the pulley 9. Each drum 105 of thecounter has a cam on its periphery which actuates an arm 106 of springmetal fixed at one end and having a contact 107 at its other endassociated with a contact 108. The disposition of the cams is such thatwhen a desired yardage of wire has passed through the machine allcontacts 107, 108 are closed. The switch 86 comprises a circuitincluding all of the contacts 107, 108 in series and when all of thecontacts are closed the switch is closed.

What we claim as our invention is:

1. A machine for applying an open lapping of spacing material to a barewire and for lapping an insulating tape over the spacing materialcomprising a head for applying the spacing material, a head for applyinginsulating tape from a coil of said tape, means for driving the twoheads, means for advancing the wire through the two heads, firstautomatic stopping means, brought into operation when the machine ceasesto apply the spacing material, comprising a first electric circuitincluding the wire and electric contact means urged towards, butnormally held out of contact with, the wire by the spacing material,second automatic stopping means brought into operation when the wirehaving an open lapping of spacing material ceases ,to be covered byinsulating tape, comprising a second electric circuit including the wireand second electric contact means adapted to bear against the wirebetween the turns of the spacing material when the wire ceases to becovered by the insulating tape and normally insulated from and held awayfrom the wire by the insulating tape lapped thereon, third automaticstopping means brought into operation by the making of a third electriccircuit when said coil of insulating tape is nearly used up, said thirdelectric circuit including electric contact means normally held open bysaid coil of insulating tape and fourth automatic stopping'meanscomprising means for measuring the length of wire passing through themachine and an electric circuit rnade thereby when a predeterminedlength of wire has passed through the machine, each of said automaticstopping means being adapted to stop the means for advancing the wirethrough the two heads and the means for driving said heads.

2. A machine according to claim 1 driven by a single electric motor,wherein each automatic stopping means operates by reversing the powersupply to the field coils of the motor for a controlled time.

3. A machine for lapping an insulating tape on to a wire over an openlapping of spacing material comprising a head for applying theinsulating tape from a coil of said tape, driving means for rotating thehead, driving means for advancing the wire through the head andautomatic stopping means for said driving means which is brought intooperation when the wire having an open lapping of spacing materialceases to be covered by insulating tape, the automatic stopping meansincluding an electric circuit comprising the wire and at least oneelectric contact which is adapted to bear against the wire between theturns of the spacing material when the wire ceases to be covered by theinsulating tape and which is normally insulated from and held away fromthe wire by the insulating tape lapped thereon.

4. A machine according to claim 3 driven by a single electric motor,wherein the automatic stopping means op crates by reversing the powersupply to the field coils of the motor for a controlled time.

5. A machine for lapping an insulating tape on to a wire over an openlapping of spacing material comprising a head for applying theinsulating tape from a coil of said tape, driving means for rotating thehead, driving means for advancing the wire through the head andautomatic stopping means for said driving means which is brought intooperation when the wire having an open lapping of spacing materialceases to be covered by insulating tape, the automatic stopping meansincluding an electric circuit comprising the wire and a member ofcontacts which are electrically connected, which are carried by a singlemember and which are adapted to bear against the wire between the turnsof the spacing material when the wire ceases to be covered by theinsulating tape, the contacts being normally insulated from and heldaway from the wire by the insulating tape lapped thereon;

6. A machine according to claim 5 driven by a single electric motor,wherein the automatic stopping means operates by reversing the powersupply to the field coils of the motor for a controlled time.

7. A machine for lapping an insulating tape onto a wire over an openlapping of spacing material comprising a head for applying theinsulating tape from a coil of said tape, driving means for rotating thehead, driving means for advancing the wire through the head andautomatic stopping means for said driving means which is brought intooperation when the wire having an open lapping of spacing materialceases to be covered by insulating tape, the automatic stopping meansincluding an electric circuit comprising the wire and a pulley overwhich the wire passes in its path from the insulating tape lapping head,the pulley being so shaped as to provide a number of electric contactswhich touch the wire when the wire ceases to be covered by theinsulating tape, the contacts being normally insulated from and heldaway from the wire by the insulating tape lapped thereon.

8. A machine according to claim 7 driven by a single electric motor,wherein the automatic stopping means operates by reversing the powersupply to the field coils of the motor for a controlled time.

9. A machine according to claim 7 in which the pulle is provided withcontacts consisting of conductive cylinders mounted transversely in thepulley groove and spaced apart around the periphery of the pulley by adistance which is not equal to and is not a multiple of the lay of thespacing material.

10. A machine for applying an open lapping of spacing material to a barewire and for lapping an insulating tape over the spacing material,comprising a head for applying the spacing material, a head for applyinginsulating tape from a coil of said tape, driving means for the heads,driving means for advancing the Wire through the two heads, firstautomatic stopping means for. said driving means, brought into operationwhen the machine ceases to apply the spacing material, comprising afirst electric circuit including the wire and electric contact meansurged towards, but normally held out of contact with, the wire by thespacing material and second automatic stopping means tor said drivingmeans, brought into operation when the wire having an open lapping ofspacing material ceases to be covered by insulating tape, comprising asecond electric circuit including the wire and a number of contactswhich are electrically connected, which are carried by a single memberand which are adapted to bear against the wire between the turns of thespacing material when the wire ceases to be covered by the insulatingtape, the contacts being normally insulated from and held away from thewire by the insulating tape lapped thereon.

11. A machine for lapping an insulating tape on to a wire over an openlapping of spacing material, comprising a head for applying theinsulating tape from a coil of said tape in the form of a flat padsupported coaxially with the wire, driving means for the head, drivingmeans for advancing the tape through the head, first automatic stoppingmeans for said driving means, which is brought into operation when thewire having an open lapping of spacing material ceases to be covered bythe insulating tape, including a first electric circuit including thewire and at least one electric contact which is adapted to bear againstthe wire between the turns of the spacing material when the wire ceasesto be covered by the insulating tape and which is normally held awayfrom the wire by the insulating tape lapped thereon and second automaticstopping means for said driving means comprising a second elect-riccircuit including a spring arm mounted at one end on a table, which isrotated about the wire, and formed at its other end with a contactmember which is normally pressed on to the pad near its centre by thearm but which is adapted to engage an insulated contact on the table,when the pad is nearly used up, to complete the second electric circuit.

12. A machine for lapping an insulating tape on to a wire over an openlapping of spacing material, comprising a head for applying theinsulating tape from a coil of said tape, driving means for the head,driving means for advancing the wire through the head, first automaticstopping means for said driving means comprising means for measuring thelength of wire passing through the machine and an electric circuit madethereby when a predetermined length of wire has passed through themachine and second automatic stopping means for said driving means,brought into operation when the wire having an open lapping of spacingmaterial ceases to be covered by insulating tape, comprising a secondelectric circuit including the wire and a number of contacts which areelectrically connected, which are carried by a single member and whichare adapted to bear against the wire between the turns of the spacingmaterial when the wire ceases to 10 be covered by the insulating tape,the contacts being normally insulated from and held away from the wireby the insulating tape lapped thereon.

13. A machine for lapping an insulating tape on to a wire over an openlapping of spacing material, comprising a head for applying theinsulating tape from a coil of said tape, a single electric motor fordriving the head, driving means for advancing the wire through the head,automatic stopping means for said motor which is brought into operationwhen the wire having an open lapping of spacing material ceases to becovered by insulating tape, the automatic stopping means including anelectric circuit comprising the wire and at least one electric contactwhich is adapted to bear against the wire between the turns of thespacing material when the Wire ceases to be covered by the insulatingtape and which is normally insulated from and held away from the wire bythe insulating tape lapped thereon, and a head guard normally enclosingthe insulating tape lapping head and formed of a fixed part and amovable part hinged to the fixed part and including an electric switchcontrolling the motor circuit in such a way that when the head guard isclosed the switch is closed automatically and when the head guard isopened the switch is opened automatically.

14. A machine for lapping an insulating tape on to a wire over an openlapping of spacing material comprising a head for applying theinsulating tape from a coil of said tape, driving means for rotating thehead, driving means for advancing the wire through the head, automaticstopping means for said driving means which is brought into operationwhen the wire having an open lapping of spacing material ceases to becovered by insulating tape, the automatic stopping means including anelectric circuit comprising the wire and at least one electric contactwhich is adapted to bear against the wire between the turns of thespacing material when the wire ceases to be covered by the insulatingtape and which is normally insulated from and held away from the wire bythe insulating tape lapped thereon and a head guard normally enclosingthe insulating tape lapping head and formed of a fixed part and amovable part hinged to the fixed part, the two parts being adapted to besecured together by a lock which prevents the movable part from beingmoved firom its enclosing position to an open position until the speedfor rotation of the tape lapping head has fallen to a low value.

References Cited in the file of this patent UNITED STATES PATENTS621,735 Arnold Mar. 21, 1899 1,368,489 Crumley Feb. 15, 1921 1,782,403Bouvier Nov. 25, 1930

